1. Field
The present disclosure relates generally to telecommunications, and more particularly, to systems and methods to retrieving call set-up information for a mobile communications device in a power efficient manner.
2. Background
The demand for wireless information services has led to the development of an ever increasing number of wireless networks. CDMA2000 1x is just one example of a wireless network that provides wide area telephony and data services. CDMA2000 1x is a wireless standard promulgated by the Third Generation Partnership Project 2 (3GPP2) using code division multiple access (CDMA) technology. CDMA is a technology that allows multiple users to share a common communications medium using spread-spectrum processing. A competing wireless network that is commonly employed in Europe is Global System for Mobile Communications (GSM). Unlike CDMA2000 1x, GSM uses narrowband time division multiple access (TDMA) to support wireless telephony and data services. Some other wireless networks include General Packet Radio Service (GPRS) which supports high speed data services with data rates suitable for e-mail and web browsing applications, and Universal Mobile Telecommunications System (UMTS) which can deliver broadband voice and data for audio and video applications.
These wireless networks can generally be thought of as wide area networks employing cellular technology. Cellular technology is based on a topology in which the geographic coverage region is broken up into cells. Within each of these cells is a fixed base transceiver station (BTS) that communicates with mobile users. A base station controller (BSC) is typically employed in the geographic coverage region to control the BTSs and route communications to the appropriate gateways for the various packet-switched and circuit-switched networks.
Interest in improving the mobile communications devices that take advantage of these various wireless wide area network technologies is almost as great as the interest in improving the underlying technologies themselves. More specifically, power management, or power conservation, techniques that extend or prolong the life of the batteries used in mobile communications devices has been one area of particular interest. One common technique used in cellular CDMA networks involves the use of a paging channel and, sometimes, a quick paging channel. A paging channel is often used to notify a mobile device, such as a cellular telephone or another type of wireless terminal, that an incoming request to communicate is pending for the mobile device. The use of such a paging channel allows the mobile device to be in a low-power mode, often referred to as “sleep mode”, at all times except for its assigned time slot for listening to the paging channel. If no call is pending, then the mobile device need only remain active long enough to listen to its assigned slot on the paging channel before returning to the sleep mode. Another technique is to use a quick paging channel in which the mobile device listens to the quick paging channel for even a briefer period of time to determine if it should stay active long enough to listen to its slot on the paging channel.
As the demand for wireless information services continue to increase, mobile devices are evolving to support integrated voice, data, and streaming media while providing seamless network coverage between wide area cellular networks and wireless local area networks (LAN). Wireless LANs generally provide telephony and data services over relatively small geographic regions using a standard protocol, such as IEEE 802.11, Bluetooth, or the like. The existence of wireless LANs provides a unique opportunity to increase user capacity in a wide area cellular network by extending cellular communications to the unlicensed spectrum using the infrastructure of the wireless LAN.
However, unlike in CDMA and other cellular networks, access to the transmission medium in a wireless LAN occurs in an asynchronous or random manner. Accordingly, the traditional CDMA paging channel or quick paging channel, previously described which relies on the mobile devices being synchronized to a common clock, cannot be implemented in the wireless LAN environment. In some wireless LAN environments, no power saving modes are contemplated and, therefore, the mobile communications devices using such a wireless LAN are always in an active mode. In other instances, certain wireless LAN technologies have implemented some type of power saving techniques by a periodic broadcast of information packets identifying which mobile devices have waiting data (e.g., TIM packets within the 802.11b/g networks). However, without any synchronizing information to know when the information packet will be broadcast, a mobile device must remain in an active mode for at least the time interval between the information packet broadcasts to ensure the mobile device is made aware of the waiting data in a timely manner. While this latter technique does provide some power savings, it remains inefficient at conserving power and prolonging battery life in mobile communications devices.
Thus, regardless of whether a mobile communications device is primarily communicating via a wireless LAN or a wide area cellular network, efficient power management so as to prolong battery life remains an important consideration in system and device design.